Structure of aggregates of trans-4-alkoxy-4'-carboxystilbenes in the solid state and in microheterogeneous media. A link between the ''unit aggregate'' and extended arrays

Crystals of three 4-alkoxy-4'-carboxy trans-stilbene (ACS) derivatives and a crystal of 4-methoxy-4'-methanoate trans-stilbene have been shown to have structures in which the amphiphilic aromatics are arranged in layers remarkably similar to deposited Langmuir-Blodgett multilayer assemblies. Within each layer there is either a glide or pseudoglide (or herringbone) arrangement of the chromophores very similar to that deduced from physical properties and simulations for structurally related stilbene, azobenzene, and tolan amphiphiles in microheterogeneous media, solution, and Langmuir-Blodgett (LB) films. The fluorescence of the crystals is very similar to that associated with LB films of a water-insoluble amphiphilic ACS that is associated with the aggregate. An analysis of the crystal structure indicates that energetically favorable aromatic-aromatic (edge-face) interaction determines the packing within a layer.